/Engine/Plugins/Experimental/Water/Source/Runtime/Public/WaterBodyActor.h
Populate the duplication seed when duplicating the actor for PIE. This allows objects to be remapped to existing objects rather than duplicating.
virtual void PopulatePIEDuplicationSeed ( [AActor::FDuplicationSeedInterface](API\Runtime\Engine\GameFramework\AActor\FDuplicationSeedInterface) & DupSeed )